Two-step atomic layer deposition of copper layers

Abstract

A method of forming copper films at low temperatures is provided. The method comprises two steps of forming a copper oxide layer from a non-fluorine containing copper precursor on a substrate and reducing the copper oxide layer to form a copper layer on the substrate. The formation of copper oxide is carried out by atomic layer deposition using a non-fluorine containing copper precursor and an oxygen containing gas at a low temperature. Copper alkoxides, copper β-diketonates and copper dialkylamides are preferred copper precursors. The reduction of copper oxide layer formed is carried out using a hydrogen containing gas at a low temperature.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of and priority to U.S. Provisional Patent Application No. 60 / 419,633 filed Oct. 17, 2002, the disclosure of which is hereby incorporated by reference in its entirety.FIELD OF THE INVENTION[0002]The present invention relates generally to the field of semiconductors. More specifically, the present invention relates to deposition of copper films for manufacturing semiconductor devices.BACKGROUND OF THE INVENTION[0003]Copper (Cu) has emerged as an alternative interconnect metal to conventional aluminum in integrated circuitry (IC) device fabrication due to its low resistivity and good electromigration properties. Several deposition techniques, such as physical vapor deposition (PVD), chemical vapor deposition (CVD), and electrochemical plating have been used for copper “damacene” interconnect fabrication. Both PVD and plating methods suffer from difficulty in filling copper in narrow and deeply trenched st...

AI Technical Summary

Benefits of technology

[0006]In general, the present invention provides a method of forming copper films on a substrate. In one embodiment, the method comprises the steps of forming a copper oxide layer from a non-fluorine containing copper precursor on a substrate and reducing the copper oxide layer to form a copper layer on the substrate. The formation of copper oxide is carried out by atomic layer deposition using a non-fluorine containing copper precursor and an oxygen containing gas at a low temperature below 200° C. Copper alkoxides, copper β-diketonates and copper dialkylamides are preferred copper precursors. The reduction of the copper oxide layer formed is carried out using a hydrogen containing gas at a low temperat

Problems solved by technology

Both PVD and plating methods suffer from difficulty in filling copper in narrow and deeply trenched structures and such methods form voids that lead to defect formation.

Another problem of prior art techniques for CVD of copper films using hfac-based copper precursors is the incorporation of trace amount of fluorine atoms at the interface between the substrate and copper layer, which degrades adhesion of the copper layer to the substrate.

This causes problems when the deposited copper films undergo a chemical mechanical polishing (CMP) step to fabricate the copper interconnect structure in the back-end-of-line IC processing.

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